Duplex locking receptacle with isolated third wire

ABSTRACT

A DUPLEX LOCKING OUTLET IS PROVIDED TO RECEIVE LOCKING CAPS WITH THREE POWER BLADES, EACH OF WHICH IS TO RECEIVE POWER. MORE SPECIFICALLY, THE DUPLEX LOCKING OUTLET IS ADAPTED TO SUPPLY TWO SEPARATE LEVELS OF VOLTAGE TO POWER BLADES INSERTED THEREIN DUE TO AN ISOLATED THIRD WIRE CONSTRUCTION.

g Feb. 23, 1971 MARTIN 3,566,337

3 DUPLEX LOCKING RECEPTACLE WITH ISOLATED THIRD WIRE Filed Oct; 30, 1968 2 Sheets-Sheet l 6%| lrnfiillllllmll Inventor Robert L. Marbl'n 5 WM 1 floP/ jdmk Attovne g Feb. 23,1971: 7 R. L. MARTIN j 3,566,331

DUPLEX LOCKING RECEPTACLE WITH ISOLATED THIRD WIRE Filed 0014.30. 1968 -2 Sheets-Sheet 2 nun 'Ihvehbor' Robert L. Martm y FM 6,4

Attorngy United States Patent ()ifice Patented Feb. 23, 1971 3,566,337 DUPLEX LOCKING RECEPTACLE WITH ISOLATED THIRD WIRE Robert L. Martin, Crauston, R.I., assignor to General Electric Company, a corporation of New York Filed Oct. 30, 1968, Ser. No. 771,731 Int. Cl. H01r 19/40 US. Cl. 339-132 6 Claims ABSTRACT OF THE DISCLOSURE A duplex locking outlet is provided to receive locking caps with three power blades, each of which is to receive power. More specifically, the duplex locking outlet is adapted to supply two separate levels of voltage to power blades inserted therein due to an isolated third wire construction.

Reference should be made to application Ser. No. 771,- 829 filed Oct. 30, 1968 of the same inventor filed concurrently herewith for teaching of a distinct invention relating to a locking duplex outlet structure of the same general appearance as the structure illustrated herein.

The present invention relates to duplex locking devices for supplying power to caps having blades to receive power in multiple voltage levels. More specifically, the invention relates to a duplex structure of relatively simple low cost yet reliable construction in which a third wire is incorporated in isolated relation to the other contacts from which power is delivered from the device.

Generally, locking devices are employed where a temporary connection of a power supply to a power using apparatus or machine is required and where the reliability of maintenance of supply of electric power is relatively important.

Many machines and other pieces of equipment require two levels of power as supplied through three wires. For example an electric heater and blower combination may require a 220 volt power supply for the heater and a 110 volt power supply for the electric motor energizing the blower. Such power can be conveniently supplied through a three wire outlet to a three wire plug if all three blades of the plug and corresponding contacts of the outlet are supplied the needed voltage levels.

An object of the present invention is to provide a duplex locking outlet structure of relatively simple construction.

A further object of the present invention is to provide a duplex locking outlet structure having an isolated third wire conveniently located for easy wiring of the device.

A further object of the present invention is to provide a duplex locking outlet structure adapted for low cost fabrication in a form which meets rigorous engineering specifications.

Other objects and advantages of the present invention will be in part apparent and in part pointed out in the description which follows.

In one of its broader aspects the object of the present invention may be achieved by providing a duplex convenience outlet adapted for locking engagement of power blades which comprises an insulating housing including a base and a cover, a plurality of cavities in said base adapted to hold power contacts for supply of electric power to power blades brought in contact therewith through said cover, three contact strips mounted in the base of said outlet each of said strips being connected to one contact in each of the outlets of said duplex structure, one of said contact strips being mounted at the back of the base of said housing and having a contact extending internally into the base at each of the outlets of said duplex structure, said contact strip being disposed in a sulating strip, said contact strip being provided at one end thereof with wire attachment means.

The attainment of the objectives of the present invention and the manner in which the invention may be most eifectively practiced will be clear from the description which follows. In giving this description, reference is made to the accompanying drawings in which:

FIG. 1 is an exploded view of the components of the outlet structure of the invention.

FIG. 2 is a top plan view of the outlet showing the cover in place on the outlet.

FIG. 3 is a top plan view of the outlet with the cover removed showing the relationship of the strap and internal parts of the structure.

FIG. 4 is a longitudinal sectional view through the center of the device showing the relationship of the isolated third wire electrode.

FIG. 5 is a side elevational view of the outlet showing three elements apparent from the exterior of the device.

FIG. 6 is a back plan view of the device showing the isolated third wire electrode in place in the recess in the base of the device.

Referring first to FIG. 1, a duplex outlet structure is shown in exploded view with each of the components shown in the position it holds in the assembled device with reference to the other components. Starting at the top, there is shown a cover 10 having two sets 12 and 14 of armate power blade receiving slots. A center opening 16 is aligned with a threaded opening 16a in the member below to receive a face plate mounting screw. Recesses 18 in the sides of the cover permit access to break-off tabs for split circuit wiring as described below.

Referring next to the mounting strap 20 shown in its position relative to the cover 10, it is seen that this strap has two end sections 21 and 22, two large openings 29 and 32, a cross-strip 23 and edge strips 24.

Proceeding down the components of FIG. 1, the insulating spacer 30 is provided as an insulator to separate portions of the strap 20 from corresponding portions of the contacts when the components are assembled in the insulating base 60.

With reference next to the insulating separator 30, it is formed with two side portions 28 which are exposed at the exterior of the outlet between the cover 10' and the insulating base 60. The upper portion of the side 28 is formed as a ridge 42 the inner edge of which conforms to the shape of the recess 36 in the side of the strap 20. In other words, when the strap is in place on the insulating separator 30, the ridge 42 provides an external insulating liner for the recessed portion 36 of the strap 20. A bridge 47 connects the two sides of the insulating spacer together and also nests into a channel 48 in insulating base 60 to limit the longitudinal movement of the sep arator relative to the base 60. A recess 44 shown in phantom in the underside of separator 30 is positioned to receive the boss 45 extending up from the screw terminal 56 of the contacts 40. The insulating separator is positioned accordingly over the wire terminal portions of the contacts 40 and beneath the portions of the strap 20 which are positioned above the wire terminals of the contacts.

The contacts 53 and 54 are mounted on the extending tabs 50 so that a power blade inserted between the fingers of contact 53 would be parallel to a power blade inserted between the contact fingers of contact 54. Actually the contacts 53 and 54 are formed separately from the contact strip and are mounted thereon as by rivets 51. A break-01f tab 46 permits separate voltages to be applied to contacts 53 and 54 when removed from its mid-point of the contact strip 52. The contacts 53 and 54 are also interchangeable prior to assembly and the main difference between them is the angle at which they are set relative to extending tabs of the contact strips 52.

The power supply to the contact strip is made by wires clamped to the wire terminal portions 56 of contact strip 52 either by clamping the wire between the clamp member 57 and the wire terminal strips 56 or by winding the wire about the head of a screw which functions both as a wire receiving screw head and as the screw the turning of which operates wire clamp 57 The contact strips, the screws, the wire clamps, and the blade contacts mounted thereon fit within the cavities of the insulating base 60 and are held in position therein both by the form of the cavity of the base itself and also by the insulating spacer 30 which presses down on the portions of the contact structure including the positioning bosses 45. The screw heads and wire terminal portions 56 are available at the sides of the housing at the openings 61. Wire entry into the clamping arrangement of the contacts is through the wire entry ports 67 in the base of the device as may be best seen with reference to the rear view of FIG. 6.

An isolated third wire contact strip 70 is provided to be mounted in the base 60 from the underside thereof. Referring particularly to FIG. 6, the contact strip is shown in position in a channel formed in the back of the base member 60. It consists of a generally T form of conductive metal strip having a blade contact mounted at both the intersections of the upright and cross members of the T and at the lower end of the upright member of the T. It also has wire terminals at the ends of the cross arm of the T formed of the metal of the strip bent at right angles to the cross member of the T.

Referring back to FIG. 1, the strip 70 is seen to have an upright member 71 and a cross member 72 forming the two elements of a general T form of a contact strip. Blade contact 73 is mounted by a conventional rivet 92 at the lower end of the upright member 71 of the T strip and blade contact '74 is attached by rivet 91 at the upper end of the upright member 71 and also at the midpoint of the cross arm 72 of the T strip. Wire terminals 76 at each end of the cross arm 72 are formed by bending the end section metal of the cross arm at right angles to the remainder of the cross arm itself. Wire engaging screws are threaded into the wire terminal tabs 76. A locating boss 77 fits into a recess 78 in the underside of the end of the insulating housing 60. It will be noted that the contacts 73 and 74 have the same form and are mounted in parallel relation to each other in that a blade entering between the fingers of the contact 73 will lie generally parallel to a blade entering between the fingers of contact 74.

An insulating cover 81 of the same general form as the contact strip 71 is shown in its mounting position relative to the other parts at the bottom of FIG. 1. A screw 82 serves to mount the insulating cover 81 over the contact strip 71 and also to hold the parts together in a finished assembly as shown in FIG. 4. A second screw 83 which can also be seen in FIG. 4 is the other assembly screw of the outlet and holds the cover 81 in its recess within the body 60 of the insulating housing. As is also evident from FIG. 4, the blade entering the opening 12 in the cover 10 of the outlet, engages the fingers of contact 74 although the contact itself is held to a connector strip which is mounted at the bottom of the outlet. Similarly, contact 73 mounted at the other end of contact strip 71 is disposed in a cavity 89 which extends through the base of the outlet so that a blade entering through opening 14 makes contact with fingers of the contact 73 although the contact 73 is assembled into the cavity 89 from the underside of the base 60 of the outlet structure. Rivets 91 and 92 hold the respective contact to the contact strip 71.

What is claimed is:

1. A duplex convenience outlet adapted for locking engagement of power blades which comprises an insulating housing including a base and cover a plurality of cavities in said base adapted to hold power contacts for supply of electric power to blades inserted through said cover into contact therewith three contact strips mounted in the base of said outlet each of said strips being connected to one contact in each of the outlets of said duplex structure one of said contact strips being mounted at each side of said insulating housing base and the third contact strip being mounted at the back of said insulating housing base,

the back mounted contact strip being disposed in a trough in the back of said housing base an insulating cover strip disposed over said back mounted contact strip,

a mounting strap electrically isolated from each of said blade contacts and sandwiched between the cover and the base,

and wire attachment means on each of said contact strips.

2. The article of claim 1 wherein the support of said strap between said base and cover is principally at the perimeter of said base and cover.

3. The article of claim 1 wherein the wire terminal portion of said contact strip mounted in said housing base is held in position by a boss on said wire terminal portion interlocking with a receiving recess in an insulating separator between said mounting strap and said base.

4. The device of claim 1 wherein an insulating spacer is disposed between the mounting strap and the contact strips in the base of said duplex outlet.

5. The device of claim 4 wherein the insulating spacer interlocks with a narrowed section of the mounting strap and restrains longitudinal motion of said strap.

6. The article of claim 1 wherein there is formed at the end section of the base of said housing a well opening to the back and sides of said housing and wire attachment screws mounted to said back mounted contact strip for supplying power thereto.

References Cited UNITED STATES PATENTS 2,132,851 10/1938 Johnson 173-330 3,032,736 5/1962 Howells 33914 3,314,043 4/1967 Carissimi 3391 64 3,426,216 2/1969 Smith et al. 307-412 MARVIN A. CHAMPION, Primary Examiner L. J. S-TAAB, Assistant Examiner US. Cl. X.R. 

